WASHINGTON — Two columns of Russian troops and armor rolled into Ukraine Thursday, triggering what the Ukrainian president called an “invasion” that sharply escalated an already violent and dangerous conflict.

President Petro Poroshenko canceled a planned trip to Turkey and convened an emergency meeting of his government following the incursion of at least 1,000 Russian troops into southeastern Ukraine.

“An invasion of Russian forces has taken place,” he announced.

Russia described the heavily armed fighters as “volunteers” — an explanation laughed off by Western powers that said Moscow had “outright lied.”

“The hand from behind is becoming more and more overt now,” said NATO Brigadier General Biko Tak, referring to Russia’s earlier attempts to shield its key role in supporting pro-Russian separatists.

President Obama told reporters a US military response is “not in the cards,” even as he pledged further pressure on Russia’s economy.

The president called Russia’s actions a “continuation of what’s been taking place,” without terming it an outright invasion.

“The violence is encouraged by Russia. The separatists are trained by Russia, they are armed by Russia, they are funded by Russia,” Obama said.

He said he had spoken to German Chancellor Angela Merkel and planned to meet with allies on his upcoming trip to Europe — a sign that tougher sanctions on Russia are in the works.

But he ruled out any military response despite Russia’s latest escalation. “We are not taking military action to solve the Ukrainian problem,” he said. Instead he referred to further “costs and consequences.”